Analysis of the Soil Microbiome of a Los Angeles Urban Farm

Table 6

Status of hypotheses at the conclusion of the 16St and soil classification surveys.

Hypothesis	Status	Supporting evidence	Limitations
Plant extracts can control resistant soil bacteria better than common antibiotics	Supported	High mean AOIs for eucalyptus, basil, and lavender oils	Lack quantifiable data for what constituents were responsible
Richness of bacterial CFUs at 10^-4 dilution can be predicted by soil physical and chemical properties	Supported	High R^2 value for multivariate regression, significant univariate models	Presence of antibiotic-producing bacteria should be considered as a factor to improve the model
Hydrocarbon-remediating bacteria will be present in Field 21	Supported	Methylobacteria spp.; Sequences were isolated from poplar root zone	Low number of reads overall for Methylobacteria spp.
Plant growth-promoting bacteria will be present in the Arboretum	Supported	Isolation of Streptomyces spp. and high proportion of reads for zeatin, mineral absorption, nitrogen metabolism, high relative abundance of Rhizobia	16S sequencing data are for the field at large rather than strain-specific
Field 19 will have the highest proportion of reads related to antibiotic-resistant genes	Partially supported	High proportion of vancomycin resistance and terpene degradation genes attributed to Field 19	Low amount of human disease and antimicrobial functions found in Field 19